U.S. patent number 7,344,037 [Application Number 10/892,027] was granted by the patent office on 2008-03-18 for inventory storage and retrieval system and method with guidance for load-handling vehicle.
This patent grant is currently assigned to Mi-Jack Products, Inc.. Invention is credited to Harvey E. Schmidt, Daniel Brian Zakula, Sr..
United States Patent |
7,344,037 |
Zakula, Sr. , et
al. |
March 18, 2008 |
Inventory storage and retrieval system and method with guidance for
load-handling vehicle
Abstract
An inventory storage and retrieval system and method are
provided for a shipping or storage facility. In an embodiment, the
system includes: (a) a mobile computer and radio on a load-handing
vehicle; (b) sensors on the vehicle to determine the ground
location and orientation of the vehicle; (c) encoders that
determine the position of a lifting mechanism relative to a chassis
of the vehicle; and (d) a base computer and radio that communicates
with the vehicle. The system maintains an inventory database of
items and their respective storage locations in three dimensions as
a result of the loading activity of the vehicle. The data can be
used to guide the vehicle for ground movement generally to a
storage location, appropriately orient the vehicle, and then to
move the lifting mechanism of the vehicle to deposit or retrieve
the item at a particular storage location.
Inventors: |
Zakula, Sr.; Daniel Brian
(Mokena, IL), Schmidt; Harvey E. (Flossmoor, IL) |
Assignee: |
Mi-Jack Products, Inc. (Hazel
Crest, IL)
|
Family
ID: |
39182150 |
Appl.
No.: |
10/892,027 |
Filed: |
July 15, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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10298487 |
Nov 18, 2002 |
7032763 |
|
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60487436 |
Jul 15, 2003 |
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Current U.S.
Class: |
212/344; 212/270;
701/41; 701/44 |
Current CPC
Class: |
B66C
13/46 (20130101); B66C 13/48 (20130101); B66C
19/007 (20130101); B66F 9/063 (20130101); B66F
9/0655 (20130101); G06Q 10/08 (20130101); G06Q
10/087 (20130101); G06Q 50/30 (20130101) |
Current International
Class: |
B66C
19/00 (20060101) |
Field of
Search: |
;212/270,344
;701/2,41,44,50 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Brahan; Thomas J.
Attorney, Agent or Firm: Drinker Biddle & Reath LLP
Parent Case Text
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This patent application is a continuation-in-part of copending U.S.
patent application Ser. No. 10/298,487, filed Nov. 18, 2002, and
this patent application claims the benefit of U.S. Provisional
Patent Application No. 60/487,436 filed Jul. 15, 2003.
Claims
What is claimed is:
1. A method for managing an inventory comprising: providing a
database storing item identification information for a plurality of
respective items and three dimensional storage location for each of
the respective items; transmitting the storage location information
and the item identification information to a vehicle having a
lifting mechanism operable to selectively handle at least one of
the items; determining a desired position and orientation of the
vehicle to provide access to the storage location; detecting a
present ground position of the vehicle; detecting an orientation of
the vehicle; comparing the present ground position and orientation
information to the desired ground position and orientation
information; automatically steering the vehicle along a desired
land travel path that can include at least one curved portion so
that the present position and orientation matches the desired
ground position and orientation information; detecting a vertical
position of the lifting mechanism; moving the lifting mechanism of
the vehicle to a vertical coordinate and horizontal coordinates
associated with the storage location; and updating the database to
reflect changes to the item identification information and location
information to reflect retrieval or deposit of an item from the
storage location.
2. The method of claim 1, wherein the desired ground position is
the storage location.
3. The method of claim 1, further comprising the step of
calculating a desired ground position of the vehicle that is offset
from the storage location such that the lifting mechanism of the
vehicle is positioned to reach the storage location when the
vehicle is at the desired ground position.
4. The method of claim 1, wherein the storage location information
includes orientation information used to determine a desired
orientation of the vehicle that permits access to the storage
location.
5. The method of claim 1, wherein the step of detecting a ground
position includes receiving a GPS signal.
6. The method of claim 1, whereby said retrieval or deposit
operation is determined by a respective unlatching or latching of
the lifting mechanism with respect to the respective item.
7. The method of claim 1, whereby the lifting mechanism is
selectively operable in a secured mode in which the lifting
mechanism is secured to the item and a free mode in which the
lifting mechanism is free from the item, and whereby the method
further comprises transmitting a signal indicating whether the
lifting mechanism is in the secured mode.
8. The method of claim 7, whereby the updating step includes
storing assigning location information to an item at a location at
which the item is released from the lifting mechanism.
Description
FIELD OF THE INVENTION
This invention generally pertains to vehicle guidance systems and
more particularly relates to a system for guiding a vehicle to
deposit and retrieve items in conjunction with inventory tracking
data.
BACKGROUND OF THE INVENTION
A guidance system for a gantry crane is disclosed in U.S. patent
application Ser. No. 10/298,487, incorporated herein by reference
in its entirety. The guidance system of that application uses GPS
technology to determine the ground position and orientation of a
gantry crane, thereby providing directional data useful for
automatically or manually driving a vehicle such as a gantry crane
to a desired location.
Various load handling systems are known, such as those disclosed in
U.S. Pat. Nos. 5,512,902, 6,266,008, and 6,577,921, and in
International Publication No. 98/34127.
A need exists for an improved system and method for utilizing a
guided vehicle to handle items in an inventory.
BRIEF SUMMARY OF THE INVENTION
The present application relates to an inventory storage and
retrieval system that utilizes one or more coordinate systems for
tracking storage locations and items associated with those
locations. The location information is used to guide a
load-handling vehicle to a particular item. Moreover, the location
information is used to manage inventory data that is updated as
items are deposited or retrieved from the locations with the
vehicle.
The system manages an inventory of items respectively stored at
predetermined positions within a storage facility defined by
three-dimensional coordinates. The system keeps track of the
location of each item with such coordinates. The location
information may be used to guide a load-handling vehicle for
depositing and retrieving the items. The system is particularly
useful for managing and moving shipping containers stored in a
stacked manner within a shipping facility, wherein the loading
vehicle is a land-traveling unit (e.g., a gantry crane, packer,
side loader, forklift, etc.) or a rail-traveling unit.
To track the inventory, the system uses a combination of GPS and
other sensor technology on the load handing vehicle to assist in
guiding the vehicle to an appropriate ground position and to allow
precise positioning of a vertically-movable lifting member of the
vehicle, for example a grappler or spreader of a gantry crane, or
an extendible grappler of a side-loader style vehicle. According to
various embodiments, the system is programmed to supplement the GPS
position data with predetermined parameters (fixed dimensions of
the vehicle, etc.) as well as encoder data that reflects the
position of the lifting device on the vehicle, resulting in an
accurate grappler and container position. Of course, the system may
be adapted for various types of load-handling vehicles, which may
have different types of encoder devices.
More specifically, the GPS data represents a position of a GPS
receiver mounted to a fixed point on a main portion of the loading
vehicle (e.g., the GPS receiver may be mounted to a beam or cab of
a gantry crane). However, the true position of an item held by the
loading vehicle is determined by the position of a lifting device
of the vehicle. The lifting device is movable relative to a main
portion or chassis of the vehicle. Encoders are used to determine
the position of the lifting device relative to the main portion of
the vehicle. Separate encoders are provided for each degree of
freedom. For example, in a side loader or packer, in which the
lifting device is vertically movable relative to the main portion,
the encoder determines a supplemental Z distance of the lifting
device relative to the GPS receiver(s). In a vehicle wherein the
lifting device is movable in a side-to-side and/or front-to-rear
direction, respective encoders are provided to measure supplemental
X and Y distances of the lifting device with respect to a
predetermined point, such as the GPS receiver(s). The encoders may
be any appropriate type of encoder or sensor for example,
mechanical, magnetic, or optical. These encoders can, for example,
measure the degree of actuation of a cylinder or a feed distance of
a cable.
In an embodiment, another factor in determining the actual position
of an item is data representing the orientation of the loading
vehicle. Based on the vehicle orientation, the system adjusts for
known structural parameters of the loading vehicle to determine the
position of the item with respect to the GPS receiver(s). For
example, in a system wherein the lifting device is mounted on a
particular side of the vehicle, the lifting device may be at a
fixed horizontal position relative to the GPS receiver(s), and the
orientation information permits the system to determine the precise
position of the lifting device (and therefore a container) with
respect to the ground. Orientation information may be determined by
the use of multiple, horizontally spaced GPS receivers.
Alternatively, orientation information may be determined by other
appropriate means, such as a compass, gyroscope, particularly in a
system wherein the vehicle includes a single GPS receiver.
Orientation data may be unnecessary in a system wherein the
orientation of the vehicle is known, such as for certain loading
vehicles maintains a fixed orientation with respect to rails.
In an embodiment, the system keeps track of whether an item is in a
stationary mode for storage or in transit. For example, the system
determines whether a container is "unlatched" or "latched" with
respect to a grappler of the loading vehicle. While the container
is "unlatched," the system stores a record of the position of the
container, which remains stationary at a position last deposited
(switched from "latched" to "unlatched") by the vehicle. If the
container is "latched," the position of the container is being
moved to a destination location, and the system stores an updated
position for the container where it is deposited at the moment it
is "unlatched" from the loading vehicle.
Various configurations are possible, such as those described in the
following examples.
In a system used with a loading vehicle having a land-traveling
traveling configuration, at least one GPS receiver can be used to
track positions along two dimensions (e.g., X and Y). Other
encoders or sensors are implemented to supplement the GPS data to
reflect the position of the lifting device relative to the GPS
receiver. For example, an encoder can be used to determine position
in a height dimension (Z). The system determines orientation, such
as by the relative positions of multiple GPS receivers or through a
dedicated orientation sensor (compass, etc.).
Where the loading vehicle is a rail-traveling unit, a GPS receiver
needs only to track positions along one dimension (e.g. X), because
the rail is fixed in a known position.
The hardware includes at least one GPS antenna and receiver,
wireless radio, electronic controller, on board server, and ground
station. The software enables the operation of the hardware for
purposes of position and control. The software may include
operating programs, utility programs, conversion programs, and
language processors including compilers, assemblers, and
translators.
The system generates an output that indicates a position relative
to a local coordinate system based on a "Latch" or "Unlatch"
activity:
TABLE-US-00001 X position 6 places in tenths of feet Y position 4
places in tenths of feet Z position 4 places in tenths of feet
In an embodiment, a variation of the system uses the container
location coordinates for guiding movement of the loading
vehicle.
In an embodiment, an advantage of the present invention is that it
provides an improved system and method for tracking an
inventory.
A further advantage of the present invention is that it provides an
improved system and method for guiding load-handling vehicles in an
environment with tracked items.
Yet another advantage of the present invention is that it provides
an accurate system and method of determining a location of a
lifting device of a load-handling vehicle.
These and other advantages of the invention will be apparent from
the description of the invention provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a load-handling vehicle on the ground
with relation to a base station and a plurality of orbiting global
positioning satellites.
FIG. 2 is a rear elevation of a rubber tire gantry crane suitable
for use a load-handling vehicle according to teachings of the
present invention.
FIG. 3 is a side elevation of a side loader suitable for use as a
load-handling vehicle according to teachings of the present
invention.
FIG. 4 is a flow chart illustrating an exemplary process for
managing an inventory according to teachings of the present
invention.
FIG. 5 is a schematic diagram of a system according to teachings of
the present invention.
FIG. 6 is a schematic plan view of a vehicle approaching an item to
be retrieved, the crane having present vehicle orientation
.PHI..sub.VP that matches a desired vehicle orientation
.PHI..sub.VD.
FIG. 7 is a schematic plan view of a vehicle parked at a desired
ground position wherein the lifting mechanism must be moved a
lateral distance .DELTA.L to latch the item located at the actual
storage location position X.sub.S1, Y.sub.S1, Z.sub.S1.
DETAILED DESCRIPTION OF THE INVENTION
The following examples further illustrate the invention but, of
course, should not be construed as in any way limiting its
scope.
Referring to FIG. 1, a storage facility is illustrated having a
base station 100, at least one load-handling vehicle 200 that
travels on the ground, and a plurality of items 30 located at
various storage locations in the facility. A three-dimensional
matrix is used for determining the locations of the vehicle 200 and
items relative to axes X, Y, and Z. For example, as shown in FIG.
1, an actual storage location of an item is indicated as X.sub.S,
Y.sub.S, Z.sub.S, and a present ground position of the vehicle is
X.sub.VP, Y.sub.VP, Z.sub.VP. A plurality of orbiting global
positioning satellites 40 is illustrated.
The vehicle 200 has a movable lifting device 250 that is configured
to lift at least one of the items 30. The items 30 illustrated
herein are standard shipping containers of a generally known type,
which have latching structures located at the respective upper
corners of each container. The lifting device 250 includes four
twistlocks operable to selectively latch and unlatch the item 30.
The invention herein will be described to the illustrated example,
however, it will be understood that the invention may be used with
an inventory of any type of corresponding vehicle, lifting device,
and item. For example, in various embodiments, the lifting device
may a spreader for lifting an item such as a truck trailer, or the
vehicle could be a forklift. Those skilled in the art will also
recognize that the items 30 may be placed in storage locations on
the ground, stacked on top of each other, or vertically arranged on
racks or shelves.
To demonstrate the versatility of the invention to various
environments, the figures herein illustrate load-handling vehicles
having different configurations. For example, FIG. 2 illustrates a
load-handling vehicle 200A configured as a rubber tire gantry
crane, and FIG. 3 illustrates a load-handling vehicle 200B in a
configuration known as a side loader.
The gantry crane vehicle 200A of FIG. 2 includes a frame or chassis
comprising vertical columns 202 connected by horizontal beams 204.
The chassis is mounted on wheels 206 operable to drive and maneuver
the vehicle 200A on the ground. The vehicle 200A includes a lifting
device 250A configured as a grappler for lifting standard shipping
containers. The exemplary vehicle 200A includes a
vertically-movable stabilizer beam 206. The lifting device 250A is
suspended from the stabilizer beam 208 by a trolley 210 that is
mounted for horizontal movement transversely along the stabilizer
beam 208. As a result, the lifting device 250A is movable relative
to the chassis in horizontal and vertical directions.
The side loader vehicle 200B of FIG. 3 includes a chassis 260 that
is equipped with wheels 262 for driving and maneuvering the vehicle
on the ground. The vehicle 200B also includes a lifting device 250B
mounted on a boom 264. As illustrated, the lifting device 250B is
configured to latch standard shipping containers. The boom 264 is
pivotally and telescopically movable for adjusting the vertical and
horizontal position of the lifting device 250B relative to the
chassis 260. More particularly, the boom 264 includes a first boom
portion 264A that is pivotally mounted to the chassis 260 at a
trunnion 265 and a second boom portion 264B that is telescopically
extendible from the first boom portion 264A. At least one linear
actuator 266 is provided for actuating pivotal motion of the first
boom portion 264A. A linear actuator (not shown) is also provided
for extending the second boom portion 264B relative to the first
boom portion 264A.
According to an aspect of the present invention, an inventory
database is maintained by tracking the locations of items moved by
the load-handling vehicle. The load-handling vehicle utilizes a
combination of GPS and other sensor technology to provide precise
position of the lifting device within a three dimensional matrix
defined by X, Y, and Z coordinates of a storage area or facility.
More particularly, one or more GPS receivers detect a general
position of the vehicle, and the position of the lifting device is
determined by detecting the current position of lifting device on
vehicle and supplementing the general vehicle location to reflect
the position of the lifting device position on the vehicle. The GPS
data is also used for guiding the vehicle to maneuver to a desired
location. The vehicle has a mobile computer that communicates via
RF with a base computer at the base station which updates the
database pursuant to loading and unloading activity. Accordingly,
the database stores current information reflecting the X, Y, and Z
storage location coordinates of items stored at the facility, which
location information may be used to accurately guide the vehicle to
retrieve or deposit selected items. In an embodiment, the database
further stores identification data that is unique per each of the
items. Also, in an embodiment, the database also stores orientation
data useful to guide the vehicle to approach the storage location
from an appropriate direction.
Referring to FIG. 5, a system is illustrated in which the base
station 100 is equipped with a base computer 112 that has access to
an inventory database 114. A two way radio, referred to herein as
transceiver 116, and corresponding antenna 118 is provided through
which the base computer 112 sends and receives RF signals. In an
embodiment, a GPS receiver 120 and corresponding GPS antenna 122
are provided at the base station 100 to provide a reference GPS
signal to the base computer 112.
At the left side of FIG. 5 is a schematic diagram of components
carried on the vehicle 200. The load-handling vehicle is equipped
with at least one mobile GPS receiver 220 having a corresponding
GPS antenna 222. The vehicle 200 includes a mobile computer 212
that receives signals from the GPS receiver 220. Additionally, the
vehicle includes a mobile two-way radio transceiver 216 through
which the mobile computer sends and receives RF signals at a
frequency corresponding to the base transceiver 116. The base and
mobile radio transceivers 116, 216 facilitate communication between
the base computer 112 and mobile computer 212 as the vehicle 200
maneuvers around the facility. To illustrate possible mounting
locations for the GPS antenna 222, FIG. 2, for example, illustrates
the vehicle 200A having a GPS antenna 222 mounted on top of the
upper horizontal beam 204, and the vehicle 200B of FIG. 3 has a GPS
antenna 222 mounted on top of a rearward portion of the chassis
260. The GPS antennae 122, 222 can be mounted in any position that
affords suitable skyward exposure for reception from the GPS
satellites 40 (FIG. 1).
The GPS data represents a position of the GPS antenna. The lifting
device is movable relative to the main portion of the vehicle
supported on the ground. Where the GPS antenna is mounted to the
main portion of the vehicle, as in the illustrated embodiments, the
GPS antenna does not indicate a precise location of the lifting
device, because the lifting device is movable relative to the GPS
antenna. In order to determine the precise position of the lifting
device and an item held by the lifting device, the vehicle is also
equipped with encoders that detect the position of the lifting
device relative to a frame or chassis of the vehicle. The position
of the lifting device (and an item held by lifting device) is
determined by adjusting the GPS position to compensate for the
position of the lifting device relative to the GPS antenna.
More specifically, as illustrated in FIG. 5, the vehicle 200 is
equipped with one or more encoders 218A, 218B to measure movement
of the lifting device and to provide a corresponding signal to the
mobile computer 212, which determines the movement or position of
the lifting device relative to the main portion of the vehicle.
Preferably separate encoders are provided for each degree of
freedom of the lifting device. Separate encoders are provided for
each degree of freedom. In an embodiment wherein the vehicle is a
forklift type of side loader or packer, wherein the lifting device
is vertically movable along the Z axis relative to the main
portion, a single encoder may be sufficient for determining a
supplemental Z distance of the lifting device relative to the GPS
receiver. In a vehicle wherein the lifting device is movable in a
side-to-side and/or front-to-rear direction, respective encoders
are provided to measure supplemental X and Y distances of the
lifting device with respect to the GPS receiver(s). The encoders
may be any appropriate type of encoder or sensor for example,
mechanical, magnetic, or optical, as are generally known. These
encoders can, for example, measure the length of actuation of a
cylinder, a feed distance of a cable, a degree of rotation of a
hoist drum for coiling a cable, or an angle of a pivotal joint, or
the degree of movement between any relatively movable
structures.
In the vehicle 200A shown in FIG. 2, the vehicle is equipped with a
first encoder (see 218A in FIG. 5) for measuring the horizontal
position of the trolley 210 relative to the stabilizer beam 210 and
a second encoder (see 218B in FIG. 5) for measuring a vertical
position of the stabilizer beam relative to the columns 202. In the
vehicle 200B of FIG. 3, a first encoder (see 218A in FIG. 5)
measures an angle of the first boom portion 264A that is pivotally
mounted to the chassis 260, and a second encoder (see 218B in FIG.
5) for measuring a relative slidable position of the telescoping
second boom portion 264B relative to the first boom portion
264A.
One or more encoders 218A, 218B (FIG. 5) measure movement of the
lifting device and provide a corresponding signal to the mobile
computer 212, which determines the movement or position of the
lifting device relative to the main portion of the vehicle.
Separate encoders are provided for each degree of freedom. For
example, in an embodiment wherein the vehicle is a forklift type of
side loader or packer, wherein the lifting device is vertically
movable relative to the main portion, the encoder determines a
supplemental Z distance of the lifting device relative to the GPS
receiver(s). In a vehicle wherein the lifting device is movable in
a side-to-side and/or front-to-rear direction, respective encoders
are provided to measure supplemental X and Y distances of the
lifting device with respect to the GPS receiver(s). The encoders
may be any appropriate type of encoder or sensor for example,
mechanical, magnetic, or optical, as are generally known. These
encoders can, for example, measure the degree of actuation of a
cylinder or a feed distance of a cable.
Referring again to FIG. 5, in an embodiment wherein the GPS
receiver 120 and corresponding antenna 122 are located at the base
station 100, the signal from the base GPS receiver 120 is sent to
the base computer 112 to be used as a reference calibration that
can be used to more precisely determine the position of the vehicle
200. In particular, the base computer 112 can be programmed to
compare the currently measured position of the antenna of the base
GPS receiver 120 to a known, fixed reference position of the
antenna 122, from which a vector can be calculated to represent the
difference between the known and measured positions. Assuming that
a similar difference between measured and actual positions
currently affects the mobile GPS receivers 220, the vector is
applied to correct the position measured by the mobile GPS
receivers 220 for improved precision.
FIG. 4 is a flow chart illustrating an exemplary process 400 for
managing an inventory according to teachings of the present
invention. Generally, steps of the process 400 result in moving an
item from a first storage location X.sub.S1 Y.sub.S1 Z.sub.S1 to a
second storage location X.sub.S2 Y.sub.S2 Z.sub.S2.
At step 405, item identification information and an actual storage
location X.sub.S1 Y.sub.S1 Z.sub.S1 are transmitted to the vehicle.
With reference to FIG. 5, the item identification and actual
storage location information are input to the base computer 112 and
transmitted via an RF signal from base transceiver 116. The base
computer 112 obtains the item identification and actual storage
location data from the inventory database 112 or by user input. The
data is received by the mobile transceiver 216 on board the vehicle
200 and is sent to the mobile computer 212. Alternatively, the item
identification and storage location X.sub.S1 Y.sub.S1 Z.sub.S1
could be entered into the mobile computer by an operator of the
vehicle.
As indicated at step 410 of FIG. 4, a present ground location
X.sub.VP Y.sub.VP is detected, and in an embodiment, a present
orientation .PHI..sub.VP of the vehicle is additionally detected.
As discussed above, in connection with FIG. 5, the present ground
location of the vehicle is preferably determined using a GPS signal
received from the GPS receiver 220 and antenna 222 on the vehicle
200. In an embodiment, another factor in determining the position
of an item is data representing the orientation of the loading
vehicle. The present orientation of the vehicle can be determined
using various techniques. For example, the vehicle may be equipped
with a second GPS receiver 220 having an antenna 222 mounted in a
laterally spaced relation from the first GPS antenna.
The present ground position of the vehicle X.sub.VP Y.sub.VP may be
the current X, Y position of one of the mobile GPS antennas 222, as
illustrated in the examples of FIGS. 2 and 3. However, those of
ordinary skill in the art will recognize the possible convenience
of adjusting the GPS position by known values particular to the
vehicle so that the present ground position X.sub.VP Y.sub.VP
represents a different point on the vehicle such as the geometric
center of the vehicle or any other point. For example, with
reference to FIG. 7, the present ground location of the vehicle
X.sub.VP Y.sub.VP is defined at the center of the vehicle 200A. The
mobile computer 212 (FIG. 5) determines the center X.sub.VP
Y.sub.VP based on predetermined dimensions of the vehicle and its
orientation .PHI..sub.VP by adjusting the GPS coordinates of the
GPS receiver by a corresponding vector.
The present orientation .PHI..sub.VP of the vehicle can be
determined in various ways. In an embodiment wherein the vehicle is
equipped with multiple GPS receivers 220, the mobile computer 212
can calculate the orientation of the vehicle based on the different
positions sensed by the first and second GPS receivers 220.
Alternatively, the present vehicle orientation .PHI..sub.VP may be
determined by other appropriate means, such as a compass,
gyroscope, or another suitable directional transducer, particularly
in a system wherein the vehicle includes a single GPS receiver.
Referring back to FIG. 4, step 415 optionally calculates a desired
ground location X.sub.VD1, Y.sub.VD1 of the vehicle that is offset
from the ground storage location X.sub.S1, Y.sub.S1. The desired
offset position X.sub.VD1, Y.sub.VD1 depends on the type of
vehicle, lifting device and corresponding item being lifted. For
example, the side loader style vehicle 200B to FIG. 3 needs to be
parked at a laterally offset position beside a container storage
location in order to properly position the lifting device 250B to
meet the top of the item 30. In FIG. 3, for example, the offset is
indicated as .DELTA.X, as the vehicle happens to be aligned on the
X axis as illustrated. Referring to FIG. 7, the offset is indicated
as .DELTA.L, which has components .DELTA.X and .DELTA.Y along the X
and Y axes. In FIG. 7, the desired offset is laterally under the
gantry style vehicle 200A in order to allow the vehicle to
concurrently straddle multiple stacks of items.
In step 415, a desired orientation is also calculated. In an
embodiment, it is desirable for the vehicle to approach the item
storage location from a particular angle or orientation. The
approach orientation can be necessary for access to the item,
depending on the configuration of the vehicle with respect to the
item 30 and the available free areas on pavement near the item. For
example, with respect to FIG. 6, it is desirable for the vehicle
200A to be aligned at a vehicle orientation .PHI..sub.VP to
approach the item 30 along the orientation .PHI..sub.VD of the item
30. In FIG. 6, the vehicle 200A is a gantry crane, and the item is
a shipping container. Because this vehicle 200A must straddle the
item 30 in order to land the lifting device on the container, it is
desirable that the vehicle approaches the item from an orientation
aligned longitudinally with the item 30. In a situation wherein the
side loader vehicle 200B is used, the desired orientation
.PHI..sub.VD of the item 30 would be perpendicular the orientation
illustrated in FIG. 6, because the side loader is structurally
configured to lift a shipping container from the side. Orientation
data may be unnecessary in a system wherein the orientation of the
vehicle is constant, such as for loading vehicles that move on
rails or in manual systems wherein the final approach relies upon
the judgment of the driver as to the best approach direction. The
desired orientation .PHI..sub.VD can be calculated by the base
computer 112 or the mobile computer according to stored parameters,
including the storage orientation of the device, the vehicle
configuration, predetermined pathways between obstacles or multiple
items.
In FIG. 4, reference numeral 420 indicates the step of maneuvering
the vehicle to the desired location and orientation that were
calculated in step 415. When the vehicle is at the desired
location, the ground position and orientation of the vehicle
X.sub.VP, Y.sub.VP, .PHI..sub.VP match, within an appropriate range
of tolerance, the desired ground position and orientation of the
vehicle X.sub.VD1, Y.sub.VD1, .PHI..sub.VD1. According to various
embodiments, the maneuvering step 420 can be automatic, manual, or
a combination of manual and automatic maneuvering. For example, the
vehicle can be equipped with a guidance indicator 226 (FIG. 5) to
display directions to a human operator for driving and steering the
vehicle 200 to the desired location. Optionally, the vehicle 200 is
equipped with guidance actuator 228 (FIG. 5) that is adapted to
control the drive and steering of the vehicle automatically to the
desired ground location at the desired orientation.
When the vehicle has arrived at the desired ground position, the
lifting device is then moved to the storage location X.sub.S1,
Y.sub.S1, Z.sub.S1, as indicated at step 425 of FIG. 4. For
example, with respect to the gantry crane style vehicle 200A of
FIG. 2, the lifting device may be moved to the storage location by
moving the trolley 210 and stabilizer beams 208 as necessary to
vary the position of the suspended grappler or lifting device 250A.
As FIG. 7 schematically illustrates, the lifting device would have
to be moved laterally a distance of .DELTA.L in order to be
properly positioned to land on top of the container 30. On the side
loader style vehicle 200B of FIG. 3, the lifting device is moved by
adjusting the angle and telescoping length of the boom 264.
Notably, the lifting device must be moved to an appropriate
vertical position on the Z axis according to the height of an item
30 or according to the vertical position of an item that sits on a
stack or which resides in a rack in a stacked relation to other
items. When the lifting device 250 is properly positioned relative
to the item 30 to be lifted, the lifting device is latched to the
item as indicated at step 430 in FIG. 4. Where the lifting device
250 is a grappler, as in the illustrated examples, the twistlocks
are rotated to the latched position within the receptacles of the
container.
In an embodiment, the system keeps track of whether an item is in a
stationary mode for storage or in transit. For example, the system
determines whether a container is "unlatched" or "latched" with
respect to a grappler of the loading vehicle. A signal associated
with an actuator of the latches or a latch sensor may be used to
provide a corresponding signal, as will be recognized by those
skilled in the art. Preferably, as indicated at step 435 of FIG. 4,
the mobile computer 212 signals the base computer 112 to indicate
that the represents that the item 30 is "in transit" due to the
latched condition of the lifting device, and it is assumed that the
position of the item 30 can be tracked along with the present
location of the vehicle. The base computer 112 preferably updates
the database to reflect that the particular item 30 is no longer
located at its storage location X.sub.S1, Y.sub.S1, Z.sub.S1 and
that it is now carried by the vehicle. If the container is latched,
the position of the container is being moved to a destination
location, and the system stores an updated position for the
container where it is deposited at the moment it is "unlatched"
from the loading vehicle.
As indicated at step 440, a new storage location X.sub.S2,
Y.sub.S2. Z.sub.S2, is provided to the mobile computer 212 to which
the item is to be moved and deposited. The storage location
X.sub.S2, Y.sub.S2 Z.sub.S2 can be transmitted to the mobile
computer 212 from the base computer 112 at the base station 100, or
alternatively, the storage location storage location X.sub.S2,
Y.sub.S2, Z.sub.S2, could be input by an operator aboard the
vehicle.
At step 445, the present vehicle ground location X.sub.VP Y.sub.VP
of the vehicle is determined in a manner as discussed above in
connection with step 410. By periodically updating the present
ground location X.sub.VP Y.sub.VP, the vehicle is tracked by the
mobile computer 212 and/or the base computer 112. At step 450, a
desired offset ground location X.sub.VD2, Y.sub.VD2 of the vehicle
is calculated relative to the storage location X.sub.S2, Y.sub.S2,
Z.sub.S2 in the manner discussed above in connection with step
415.
As indicated at step 455, the vehicle is maneuvered to the desired
location so that the present vehicle position X.sub.VP Y.sub.VP
matches the desired vehicle position X.sub.VD2, Y.sub.VD2, within a
suitable range of tolerance, as discussed above in connection with
step 420. The maneuvering step 455 may be manually directed by the
operator with the assistance of the guidance indicator 226 (FIG.
5), or the maneuvering may be partially or fully automated with the
assistance of the guidance actuator 228 (FIG. 5).
When the vehicle is parked at the desired vehicle ground location,
X.sub.VD2, Y.sub.VD2, the lifting device is moved to place the item
30 at rest at the desired storage location X.sub.S2, Y.sub.S2,
Z.sub.S2. This requires movement of the lifting device as discussed
above in connection with step 425. When the item is properly
positioned, the lifting device 250 is unlatched from the item 30,
as indicated by step 465. For example, in the example wherein the
lifting device is a grappler, as illustrated in FIGS. 2 and 3, the
twistlocks are moved to an unlatched position to release the
grappler from the container. The mobile computer 212 transmits a
signal to the base computer 112 that the item 30 has been
unlatched, and accordingly, the base computer 112 updates the
database to reflect that the particular item corresponds to the new
storage location X.sub.S2, Y.sub.S2, Z.sub.S2 where it was just
deposited. While the container is "unlatched," the system stores a
record of the position of the container, which remains stationary
at a position last deposited (switched from "latched" to
"unlatched") by the vehicle.
All references, including publications, patent applications, and
patents, cited herein are hereby incorporated by reference to the
same extent as if each reference were individually and specifically
indicated to be incorporated by reference and were set forth in its
entirety herein.
The use of the terms "a" and "an" and "the" and similar referents
in the context of describing the invention (especially in the
context of the following claims) are to be construed to cover both
the singular and the plural, unless otherwise indicated herein or
clearly contradicted by context. Recitation of ranges of values
herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indicating any non-claimed element as essential to the practice of
the invention.
Preferred embodiments of this invention are described herein,
including the best mode known to the inventors for carrying out the
invention. It should be understood that the illustrated embodiments
are exemplary only, and should not be taken as limiting the scope
of the invention.
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